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Do Wolves Affect White-Tailed Buck Harvest
In Northeastern Minnesota?

Discussion


Because deer constitute the main prey of wolves in our study area, it is reasonable to think that wolves would affect the number of deer harvested by humans (Mech 1971, 1984; Fuller 1989). In fact, any major factor that adds to total deer mortality would have some effect, especially if a high percentage of the deer population is harvested. An extreme example was the decimation of deer in the eastcentral part of the SNF and reduction of the surrounding population in the early 1970's. Although poor habitat and a series of severe winters contributed to the deer decline, it was exacerbated by wolves (Mech and Karns 1977). To whatever extent wolf predation added to any direct weather-caused losses, that predation affected deer hunting.

The more heavily harvested a deer population, the greater the potential for other mortality factors, including wolves, to affect the number of harvestable deer (Mech 1971, 1984; Fuller 1989). Thus, a wolf-free area should support more harvestable deer than a similar area with wolves. The degree to which wolf predation and human hunting actually compete, however, is dependent on the intensity of each and how compensatory those factors are. The greater the proportion of the herd removed by each mortality factor, the greater the probability for competition.

In our census area, wolves kill about 20% and hunters about 30% of the legal bucks, and of all yearling and adult deer of both sexes, wolves take about 15% and hunters 7% (Nelson and Mech 1986b; M. E. Nelson and L. D. Mech, U.S. Geological Survey, unpublished data). The northeastern half of the area includes soil of low fertility and poor habitat that has been protected from cutting or burning and has supported a relatively low deer density for decades (Mech and Karns 1977, Nelson and Mech 1981). In such an area, wolves and hunters would probably compete more for the relatively few deer, which may explain the stronger relationship between size of the wolf population and deer harvest.

Our findings in the present study are ambiguous about the degree to which wolves compete with hunters for bucks, and the possible masking of relationships by the unknown effect of variable hunter effort each year. Only if we had found no relationships between wolf numbers and buck harvest in all the tests we ran could we have concluded that wolves probably did not have any strong direct effect on buck harvest.

However, we did find some significant relationships between wolf numbers and buck harvest, and it is revealing that the stronger relationships were for a period when hunter effort was considered relatively constant. This finding may demonstrate that variable hunter effort can indeed mask these relationships under some conditions. However, we found the strongest relationships when deer density was lowest and competition between wolves and hunters probably greatest. In fact, in the better habitat where we had the largest samples of buck harvest data, we found no significant relationships between wolves and buck harvest even when hunter effort appeared relatively constant. This suggests that generally hunter effort may not be so overwhelming a factor that it obscures strong relationships with wolves.

Our examination of annual changes in wolf and deer numbers showed inconsistent relationships. During some years after wolves increased, buck harvest increased. Furthermore, the wolf population actually declined while deer numbers, as reflected by the buck harvest (Lenarz 1997), increased (Fig. 2).

We are uncertain about the significance of the fact that during the 8-year period when wolves seemed to be most influential, the buck harvest for the Ely area was the highest for the 14 years of records (Table 1). However, this increased harvest might have resulted from increased hunting pressure responding to an increasing deer population.

Despite the ambiguities and uncertainties in our results, it is reasonable to conclude that, at least in poor quality habitat, wolves do negatively influence deer harvest: Stenlund (1955) and Mech and Karns (1977) also came to the same conclusion. However there still is no evidence that in most areas wolves directly influence buck harvest significantly, at least under current hunting regulations.


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